Amazon Web Services

The Tarsnap service is built on top of the solid platform provided by
Amazon Web Services. Data
archived via Tarsnap is stored to the
Amazon S3 storage service
(the original version, which can survive the loss of 2 datacenters,
not the "reduced redundancy" version which can only survive the loss
of a single datacenter) before it is acknowledged by the Tarsnap
server to Tarsnap clients, so the probability of Tarsnap data being
lost due to hardware failures is extremely low — somewhere
approaching the probability of a nuclear war or meteor hit destroying
most of the US.

The Tarsnap server resides in the
Amazon EC2 compute cloud,
and at the present time it is possible — but quite unlikely
— that a hardware failure would result in the Tarsnap service
becoming unavailable until a new EC2 instance can be launched and the
Tarsnap server code can be restarted (note that this would make data
archived via Tarsnap unavailable, but would not cause it to be
permanently lost). So far such an outage has never occurred; but
over time Tarsnap will become more tolerant of failures in order to
minimize the probability that such an outage occurs in the future.

For more information (including technical details about constructing
a log-structured filesystem using S3 as back-end storage, caching
metadata in EC2, and bundling writes in order to save on S3
per-request costs), see the author's blog post from December 2008,
How
Tarsnap uses Amazon Web Services.

Payment processing: Stripe, Bitcoin, and PayPal

Tarsnap uses Stripe and
PayPal for payment processing.
Tarsnap users can make payments using credit cards directly or with
Bitcoin (both of which are processed by Stripe) or via a PayPal account
(using credit cards, bank accounts, or PayPal balances).